/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
/*-------------------------------------------------------------------------
 *
 * json.c
 *    JSON data type support.
 *
 * Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/backend/utils/adt/json.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/transam.h"
#include "catalog/pg_type.h"
#include "executor/spi.h"
#include "lib/stringinfo.h"
#include "libpq/pqformat.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "parser/parse_coerce.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/date.h"
#include "utils/datetime.h"
#include "utils/lsyscache.h"
#include "utils/json.h"
#include "utils/jsonapi.h"
#include "utils/typcache.h"
#include "utils/syscache.h"

/* String to output for infinite dates and timestamps */
#define DT_INFINITY "\"infinity\""

/*
 * The context of the parser is maintained by the recursive descent
 * mechanism, but is passed explicitly to the error reporting routine
 * for better diagnostics.
 */
typedef enum          /* contexts of JSON parser */
{
  JSON_PARSE_VALUE,     /* expecting a value */
  JSON_PARSE_STRING,      /* expecting a string (for a field name) */
  JSON_PARSE_ARRAY_START,   /* saw '[', expecting value or ']' */
  JSON_PARSE_ARRAY_NEXT,    /* saw array element, expecting ',' or ']' */
  JSON_PARSE_OBJECT_START,  /* saw '{', expecting label or '}' */
  JSON_PARSE_OBJECT_LABEL,  /* saw object label, expecting ':' */
  JSON_PARSE_OBJECT_NEXT,   /* saw object value, expecting ',' or '}' */
  JSON_PARSE_OBJECT_COMMA,  /* saw object ',', expecting next label */
  JSON_PARSE_END        /* saw the end of a document, expect nothing */
} JsonParseContext;

typedef enum          /* type categories for datum_to_json */
{
  JSONTYPE_NULL,        /* null, so we didn't bother to identify */
  JSONTYPE_BOOL,        /* boolean (built-in types only) */
  JSONTYPE_NUMERIC,     /* numeric (ditto) */
  JSONTYPE_DATE,        /* we use special formatting for datetimes */
  JSONTYPE_TIMESTAMP,
  JSONTYPE_TIMESTAMPTZ,
  JSONTYPE_JSON,        /* JSON itself (and JSONB) */
  JSONTYPE_ARRAY,       /* array */
  JSONTYPE_COMPOSITE,     /* composite */
  JSONTYPE_CAST,        /* something with an explicit cast to JSON */
  JSONTYPE_OTHER        /* all else */
} JsonTypeCategory;

typedef struct JsonAggState
{
  StringInfo         str;
  JsonTypeCategory   key_category;
  Oid                key_output_func;
  JsonTypeCategory   val_category;
  Oid                val_output_func;
} JsonAggState;

static inline void json_lex(JsonLexContext *lex);
static inline void json_lex_string(JsonLexContext *lex);
static inline void json_lex_number(JsonLexContext *lex, char *s, bool *num_err);
static inline void parse_scalar(JsonLexContext *lex, JsonSemAction *sem);
static void parse_object_field(JsonLexContext *lex, JsonSemAction *sem);
static void parse_object(JsonLexContext *lex, JsonSemAction *sem);
static void parse_array_element(JsonLexContext *lex, JsonSemAction *sem);
static void parse_array(JsonLexContext *lex, JsonSemAction *sem);
static void report_parse_error(JsonParseContext ctx, JsonLexContext *lex);
static void report_invalid_token(JsonLexContext *lex);
static int  report_json_context(JsonLexContext *lex);
static char *extract_mb_char(char *s);
static void composite_to_json(Datum composite, StringInfo result,
          bool use_line_feeds);
static void array_dim_to_json(StringInfo result, int dim, int ndims, int *dims,
          Datum *vals, bool *nulls, int *valcount,
          JsonTypeCategory tcategory, Oid outfuncoid,
          bool use_line_feeds);
static void array_to_json_internal(Datum array, StringInfo result,
             bool use_line_feeds);
static void json_categorize_type(Oid typoid,
           JsonTypeCategory *tcategory,
           Oid *outfuncoid);
static void datum_to_json(Datum val, bool is_null, StringInfo result,
        JsonTypeCategory tcategory, Oid outfuncoid,
        bool key_scalar);
static void add_json(Datum val, bool is_null, StringInfo result,
     Oid val_type, bool key_scalar);
static text *catenate_stringinfo_string(StringInfo buffer, const char *addon);

/* the null action object used for pure validation */
static JsonSemAction nullSemAction =
{
  NULL, NULL, NULL, NULL, NULL,
  NULL, NULL, NULL, NULL, NULL
};

/* Recursive Descent parser support routines */

/*
 * lex_peek
 *
 * what is the current look_ahead token?
*/
static inline JsonTokenType
lex_peek(JsonLexContext *lex)
{
  return lex->token_type;
}

/*
 * lex_accept
 *
 * accept the look_ahead token and move the lexer to the next token if the
 * look_ahead token matches the token parameter. In that case, and if required,
 * also hand back the de-escaped lexeme.
 *
 * returns true if the token matched, false otherwise.
 */
static inline bool
lex_accept(JsonLexContext *lex, JsonTokenType token, char **lexeme)
{
  if (lex->token_type == token)
  {
    if (lexeme != NULL)
    {
      if (lex->token_type == JSON_TOKEN_STRING)
      {
        if (lex->strval != NULL)
          *lexeme = pstrdup(lex->strval->data);
      }
      else
      {
        int     len = (lex->token_terminator - lex->token_start);
        char     *tokstr = palloc(len + 1);

        memcpy(tokstr, lex->token_start, len);
        tokstr[len] = '\0';
        *lexeme = tokstr;
      }
    }
    json_lex(lex);
    return true;
  }
  return false;
}

/*
 * lex_accept
 *
 * move the lexer to the next token if the current look_ahead token matches
 * the parameter token. Otherwise, report an error.
 */
static inline void
lex_expect(JsonParseContext ctx, JsonLexContext *lex, JsonTokenType token)
{
  if (!lex_accept(lex, token, NULL))
    report_parse_error(ctx, lex);
}

/* chars to consider as part of an alphanumeric token */
#define JSON_ALPHANUMERIC_CHAR(c)  \
  (((c) >= 'a' && (c) <= 'z') || \
   ((c) >= 'A' && (c) <= 'Z') || \
   ((c) >= '0' && (c) <= '9') || \
   (c) == '_' || \
   IS_HIGHBIT_SET(c))

/* utility function to check if a string is a valid JSON number */
extern bool
IsValidJsonNumber(const char *str, int len)
{
  bool    numeric_error;
  JsonLexContext dummy_lex;


  /*
   * json_lex_number expects a leading  '-' to have been eaten already.
   *
   * having to cast away the constness of str is ugly, but there's not much
   * easy alternative.
   */
  if (*str == '-')
  {
    dummy_lex.input = (char *) str + 1;
    dummy_lex.input_length = len - 1;
  }
  else
  {
    dummy_lex.input = (char *) str;
    dummy_lex.input_length = len;
  }

  json_lex_number(&dummy_lex, dummy_lex.input, &numeric_error);

  return !numeric_error;
}

/*
 * Input.
 */
Datum
json_in(PG_FUNCTION_ARGS)
{
  char     *json = PG_GETARG_CSTRING(0);
  text     *result = cstring_to_text(json);
  JsonLexContext *lex;

  /* validate it */
  lex = makeJsonLexContext(result, false);
  pg_parse_json(lex, &nullSemAction);

  /* Internal representation is the same as text, for now */
  PG_RETURN_TEXT_P(result);
}

/*
 * Output.
 */
Datum
json_out(PG_FUNCTION_ARGS)
{
  /* we needn't detoast because text_to_cstring will handle that */
  Datum   txt = PG_GETARG_DATUM(0);

  PG_RETURN_CSTRING(TextDatumGetCString(txt));
}

/*
 * Binary send.
 */
Datum
json_send(PG_FUNCTION_ARGS)
{
  text     *t = PG_GETARG_TEXT_PP(0);
  StringInfoData buf;

  pq_begintypsend(&buf);
  pq_sendtext(&buf, VARDATA_ANY(t), VARSIZE_ANY_EXHDR(t));
  PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}

/*
 * Binary receive.
 */
Datum
json_recv(PG_FUNCTION_ARGS)
{
  StringInfo  buf = (StringInfo) PG_GETARG_POINTER(0);
  char     *str;
  int     nbytes;
  JsonLexContext *lex;

  str = pq_getmsgtext(buf, buf->len - buf->cursor, &nbytes);

  /* Validate it. */
  lex = makeJsonLexContextCstringLen(str, nbytes, false);
  pg_parse_json(lex, &nullSemAction);

  PG_RETURN_TEXT_P(cstring_to_text_with_len(str, nbytes));
}

/*
 * makeJsonLexContext
 *
 * lex constructor, with or without StringInfo object
 * for de-escaped lexemes.
 *
 * Without is better as it makes the processing faster, so only make one
 * if really required.
 *
 * If you already have the json as a text* value, use the first of these
 * functions, otherwise use  makeJsonLexContextCstringLen().
 */
JsonLexContext *
makeJsonLexContext(text *json, bool need_escapes)
{
  return makeJsonLexContextCstringLen(VARDATA(json),
                    VARSIZE(json) - VARHDRSZ,
                    need_escapes);
}

JsonLexContext *
makeJsonLexContextCstringLen(char *json, int len, bool need_escapes)
{
  JsonLexContext *lex = palloc0(sizeof(JsonLexContext));

  lex->input = lex->token_terminator = lex->line_start = json;
  lex->line_number = 1;
  lex->input_length = len;
  if (need_escapes)
    lex->strval = makeStringInfo();
  return lex;
}

/*
 * pg_parse_json
 *
 * Publicly visible entry point for the JSON parser.
 *
 * lex is a lexing context, set up for the json to be processed by calling
 * makeJsonLexContext(). sem is a strucure of function pointers to semantic
 * action routines to be called at appropriate spots during parsing, and a
 * pointer to a state object to be passed to those routines.
 */
void
pg_parse_json(JsonLexContext *lex, JsonSemAction *sem)
{
  JsonTokenType tok;

  /* get the initial token */
  json_lex(lex);

  tok = lex_peek(lex);

  /* parse by recursive descent */
  switch (tok)
  {
    case JSON_TOKEN_OBJECT_START:
      parse_object(lex, sem);
      break;
    case JSON_TOKEN_ARRAY_START:
      parse_array(lex, sem);
      break;
    default:
      parse_scalar(lex, sem);   /* json can be a bare scalar */
  }

  lex_expect(JSON_PARSE_END, lex, JSON_TOKEN_END);

}

/*
 * json_count_array_elements
 *
 * Returns number of array elements in lex context at start of array token
 * until end of array token at same nesting level.
 *
 * Designed to be called from array_start routines.
 */
int
json_count_array_elements(JsonLexContext *lex)
{
  JsonLexContext  copylex;
  int       count;

  /*
   * It's safe to do this with a shallow copy because the lexical routines
   * don't scribble on the input. They do scribble on the other pointers etc,
   * so doing this with a copy makes that safe.
   */
  memcpy(&copylex, lex, sizeof(JsonLexContext));
  copylex.strval = NULL; /* not interested in values here */
  copylex.lex_level++;

  count = 0;
  lex_expect(JSON_PARSE_ARRAY_START, &copylex, JSON_TOKEN_ARRAY_START);
  if (lex_peek(&copylex) != JSON_TOKEN_ARRAY_END)
  {
    do
    {
      count++;
      parse_array_element(&copylex, &nullSemAction);
    }
    while (lex_accept(&copylex, JSON_TOKEN_COMMA, NULL));
  }
  lex_expect(JSON_PARSE_ARRAY_NEXT, &copylex, JSON_TOKEN_ARRAY_END);

  return count;
}

/*
 *  Recursive Descent parse routines. There is one for each structural
 *  element in a json document:
 *    - scalar (string, number, true, false, null)
 *    - array  ( [ ] )
 *    - array element
 *    - object ( { } )
 *    - object field
 */
static inline void
parse_scalar(JsonLexContext *lex, JsonSemAction *sem)
{
  char     *val = NULL;
  json_scalar_action sfunc = sem->scalar;
  char    **valaddr;
  JsonTokenType tok = lex_peek(lex);

  valaddr = sfunc == NULL ? NULL : &val;

  /* a scalar must be a string, a number, true, false, or null */
  switch (tok)
  {
    case JSON_TOKEN_TRUE:
      lex_accept(lex, JSON_TOKEN_TRUE, valaddr);
      break;
    case JSON_TOKEN_FALSE:
      lex_accept(lex, JSON_TOKEN_FALSE, valaddr);
      break;
    case JSON_TOKEN_NULL:
      lex_accept(lex, JSON_TOKEN_NULL, valaddr);
      break;
    case JSON_TOKEN_NUMBER:
      lex_accept(lex, JSON_TOKEN_NUMBER, valaddr);
      break;
    case JSON_TOKEN_STRING:
      lex_accept(lex, JSON_TOKEN_STRING, valaddr);
      break;
    default:
      report_parse_error(JSON_PARSE_VALUE, lex);
  }

  if (sfunc != NULL)
    (*sfunc) (sem->semstate, val, tok);
}

static void
parse_object_field(JsonLexContext *lex, JsonSemAction *sem)
{
  /*
   * An object field is "fieldname" : value where value can be a scalar,
   * object or array.  Note: in user-facing docs and error messages, we
   * generally call a field name a "key".
   */

  char     *fname = NULL; /* keep compiler quiet */
  json_ofield_action ostart = sem->object_field_start;
  json_ofield_action oend = sem->object_field_end;
  bool    isnull;
  char    **fnameaddr = NULL;
  JsonTokenType tok;

  if (ostart != NULL || oend != NULL)
    fnameaddr = &fname;

  if (!lex_accept(lex, JSON_TOKEN_STRING, fnameaddr))
    report_parse_error(JSON_PARSE_STRING, lex);

  lex_expect(JSON_PARSE_OBJECT_LABEL, lex, JSON_TOKEN_COLON);

  tok = lex_peek(lex);
  isnull = tok == JSON_TOKEN_NULL;

  if (ostart != NULL)
    (*ostart) (sem->semstate, fname, isnull);

  switch (tok)
  {
    case JSON_TOKEN_OBJECT_START:
      parse_object(lex, sem);
      break;
    case JSON_TOKEN_ARRAY_START:
      parse_array(lex, sem);
      break;
    default:
      parse_scalar(lex, sem);
  }

  if (oend != NULL)
    (*oend) (sem->semstate, fname, isnull);
}

static void
parse_object(JsonLexContext *lex, JsonSemAction *sem)
{
  /*
   * an object is a possibly empty sequence of object fields, separated by
   * commas and surrounded by curly braces.
   */
  json_struct_action ostart = sem->object_start;
  json_struct_action oend = sem->object_end;
  JsonTokenType tok;

  check_stack_depth();

  if (ostart != NULL)
    (*ostart) (sem->semstate);

  /*
   * Data inside an object is at a higher nesting level than the object
   * itself. Note that we increment this after we call the semantic routine
   * for the object start and restore it before we call the routine for the
   * object end.
   */
  lex->lex_level++;

  /* we know this will succeeed, just clearing the token */
  lex_expect(JSON_PARSE_OBJECT_START, lex, JSON_TOKEN_OBJECT_START);

  tok = lex_peek(lex);
  switch (tok)
  {
    case JSON_TOKEN_STRING:
      parse_object_field(lex, sem);
      while (lex_accept(lex, JSON_TOKEN_COMMA, NULL))
        parse_object_field(lex, sem);
      break;
    case JSON_TOKEN_OBJECT_END:
      break;
    default:
      /* case of an invalid initial token inside the object */
      report_parse_error(JSON_PARSE_OBJECT_START, lex);
  }

  lex_expect(JSON_PARSE_OBJECT_NEXT, lex, JSON_TOKEN_OBJECT_END);

  lex->lex_level--;

  if (oend != NULL)
    (*oend) (sem->semstate);
}

static void
parse_array_element(JsonLexContext *lex, JsonSemAction *sem)
{
  json_aelem_action astart = sem->array_element_start;
  json_aelem_action aend = sem->array_element_end;
  JsonTokenType tok = lex_peek(lex);

  bool    isnull;

  isnull = tok == JSON_TOKEN_NULL;

  if (astart != NULL)
    (*astart) (sem->semstate, isnull);

  /* an array element is any object, array or scalar */
  switch (tok)
  {
    case JSON_TOKEN_OBJECT_START:
      parse_object(lex, sem);
      break;
    case JSON_TOKEN_ARRAY_START:
      parse_array(lex, sem);
      break;
    default:
      parse_scalar(lex, sem);
  }

  if (aend != NULL)
    (*aend) (sem->semstate, isnull);
}

static void
parse_array(JsonLexContext *lex, JsonSemAction *sem)
{
  /*
   * an array is a possibly empty sequence of array elements, separated by
   * commas and surrounded by square brackets.
   */
  json_struct_action astart = sem->array_start;
  json_struct_action aend = sem->array_end;

  check_stack_depth();

  if (astart != NULL)
    (*astart) (sem->semstate);

  /*
   * Data inside an array is at a higher nesting level than the array
   * itself. Note that we increment this after we call the semantic routine
   * for the array start and restore it before we call the routine for the
   * array end.
   */
  lex->lex_level++;

  lex_expect(JSON_PARSE_ARRAY_START, lex, JSON_TOKEN_ARRAY_START);
  if (lex_peek(lex) != JSON_TOKEN_ARRAY_END)
  {

    parse_array_element(lex, sem);

    while (lex_accept(lex, JSON_TOKEN_COMMA, NULL))
      parse_array_element(lex, sem);
  }

  lex_expect(JSON_PARSE_ARRAY_NEXT, lex, JSON_TOKEN_ARRAY_END);

  lex->lex_level--;

  if (aend != NULL)
    (*aend) (sem->semstate);
}

/*
 * Lex one token from the input stream.
 */
static inline void
json_lex(JsonLexContext *lex)
{
  char     *s;
  int     len;

  /* Skip leading whitespace. */
  s = lex->token_terminator;
  len = s - lex->input;
  while (len < lex->input_length &&
       (*s == ' ' || *s == '\t' || *s == '\n' || *s == '\r'))
  {
    if (*s == '\n')
      ++lex->line_number;
    ++s;
    ++len;
  }
  lex->token_start = s;

  /* Determine token type. */
  if (len >= lex->input_length)
  {
    lex->token_start = NULL;
    lex->prev_token_terminator = lex->token_terminator;
    lex->token_terminator = s;
    lex->token_type = JSON_TOKEN_END;
  }
  else
    switch (*s)
    {
        /* Single-character token, some kind of punctuation mark. */
      case '{':
        lex->prev_token_terminator = lex->token_terminator;
        lex->token_terminator = s + 1;
        lex->token_type = JSON_TOKEN_OBJECT_START;
        break;
      case '}':
        lex->prev_token_terminator = lex->token_terminator;
        lex->token_terminator = s + 1;
        lex->token_type = JSON_TOKEN_OBJECT_END;
        break;
      case '[':
        lex->prev_token_terminator = lex->token_terminator;
        lex->token_terminator = s + 1;
        lex->token_type = JSON_TOKEN_ARRAY_START;
        break;
      case ']':
        lex->prev_token_terminator = lex->token_terminator;
        lex->token_terminator = s + 1;
        lex->token_type = JSON_TOKEN_ARRAY_END;
        break;
      case ',':
        lex->prev_token_terminator = lex->token_terminator;
        lex->token_terminator = s + 1;
        lex->token_type = JSON_TOKEN_COMMA;
        break;
      case ':':
        lex->prev_token_terminator = lex->token_terminator;
        lex->token_terminator = s + 1;
        lex->token_type = JSON_TOKEN_COLON;
        break;
      case '"':
        /* string */
        json_lex_string(lex);
        lex->token_type = JSON_TOKEN_STRING;
        break;
      case '-':
        /* Negative number. */
        json_lex_number(lex, s + 1, NULL);
        lex->token_type = JSON_TOKEN_NUMBER;
        break;
      case '0':
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6':
      case '7':
      case '8':
      case '9':
        /* Positive number. */
        json_lex_number(lex, s, NULL);
        lex->token_type = JSON_TOKEN_NUMBER;
        break;
      default:
        {
          char     *p;

          /*
           * We're not dealing with a string, number, legal
           * punctuation mark, or end of string.  The only legal
           * tokens we might find here are true, false, and null,
           * but for error reporting purposes we scan until we see a
           * non-alphanumeric character.  That way, we can report
           * the whole word as an unexpected token, rather than just
           * some unintuitive prefix thereof.
           */
          for (p = s; p - s < lex->input_length - len && JSON_ALPHANUMERIC_CHAR(*p); p++)
             /* skip */ ;

          /*
           * We got some sort of unexpected punctuation or an
           * otherwise unexpected character, so just complain about
           * that one character.
           */
          if (p == s)
          {
            lex->prev_token_terminator = lex->token_terminator;
            lex->token_terminator = s + 1;
            report_invalid_token(lex);
          }

          /*
           * We've got a real alphanumeric token here.  If it
           * happens to be true, false, or null, all is well.  If
           * not, error out.
           */
          lex->prev_token_terminator = lex->token_terminator;
          lex->token_terminator = p;
          if (p - s == 4)
          {
            if (memcmp(s, "true", 4) == 0)
              lex->token_type = JSON_TOKEN_TRUE;
            else if (memcmp(s, "null", 4) == 0)
              lex->token_type = JSON_TOKEN_NULL;
            else
              report_invalid_token(lex);
          }
          else if (p - s == 5 && memcmp(s, "false", 5) == 0)
            lex->token_type = JSON_TOKEN_FALSE;
          else
            report_invalid_token(lex);

        }
    }           /* end of switch */
}

/*
 * The next token in the input stream is known to be a string; lex it.
 */
static inline void
json_lex_string(JsonLexContext *lex)
{
  char     *s;
  int     len;
  int     hi_surrogate = -1;

  if (lex->strval != NULL)
    resetStringInfo(lex->strval);

  Assert(lex->input_length > 0);
  s = lex->token_start;
  len = lex->token_start - lex->input;
  for (;;)
  {
    s++;
    len++;
    /* Premature end of the string. */
    if (len >= lex->input_length)
    {
      lex->token_terminator = s;
      report_invalid_token(lex);
    }
    else if (*s == '"')
      break;
    else if ((unsigned char) *s < 32)
    {
      /* Per RFC4627, these characters MUST be escaped. */
      /* Since *s isn't printable, exclude it from the context string */
      lex->token_terminator = s;
      ereport(ERROR,
          (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
           errmsg("invalid input syntax for type json"),
           errdetail("Character with value 0x%02x must be escaped.",
                 (unsigned char) *s),
           report_json_context(lex)));
    }
    else if (*s == '\\')
    {
      /* OK, we have an escape character. */
      s++;
      len++;
      if (len >= lex->input_length)
      {
        lex->token_terminator = s;
        report_invalid_token(lex);
      }
      else if (*s == 'u')
      {
        int     i;
        int     ch = 0;

        for (i = 1; i <= 4; i++)
        {
          s++;
          len++;
          if (len >= lex->input_length)
          {
            lex->token_terminator = s;
            report_invalid_token(lex);
          }
          else if (*s >= '0' && *s <= '9')
            ch = (ch * 16) + (*s - '0');
          else if (*s >= 'a' && *s <= 'f')
            ch = (ch * 16) + (*s - 'a') + 10;
          else if (*s >= 'A' && *s <= 'F')
            ch = (ch * 16) + (*s - 'A') + 10;
          else
          {
            lex->token_terminator = s + pg_mblen(s);
            ereport(ERROR,
                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                 errmsg("invalid input syntax for type json"),
                 errdetail("\"\\u\" must be followed by four hexadecimal digits."),
                 report_json_context(lex)));
          }
        }
        if (lex->strval != NULL)
        {
          char    utf8str[5];
          int     utf8len;

          if (ch >= 0xd800 && ch <= 0xdbff)
          {
            if (hi_surrogate != -1)
              ereport(ERROR,
                 (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                errmsg("invalid input syntax for type json"),
                errdetail("Unicode high surrogate must not follow a high surrogate."),
                report_json_context(lex)));
            hi_surrogate = (ch & 0x3ff) << 10;
            continue;
          }
          else if (ch >= 0xdc00 && ch <= 0xdfff)
          {
            if (hi_surrogate == -1)
              ereport(ERROR,
                 (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                errmsg("invalid input syntax for type json"),
                errdetail("Unicode low surrogate must follow a high surrogate."),
                report_json_context(lex)));
            ch = 0x10000 + hi_surrogate + (ch & 0x3ff);
            hi_surrogate = -1;
          }

          if (hi_surrogate != -1)
            ereport(ERROR,
                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                 errmsg("invalid input syntax for type json"),
                 errdetail("Unicode low surrogate must follow a high surrogate."),
                 report_json_context(lex)));

          /*
           * For UTF8, replace the escape sequence by the actual
           * utf8 character in lex->strval. Do this also for other
           * encodings if the escape designates an ASCII character,
           * otherwise raise an error.
           */

          if (ch == 0)
          {
            /* We can't allow this, since our TEXT type doesn't */
            ereport(ERROR,
                (errcode(ERRCODE_UNTRANSLATABLE_CHARACTER),
                 errmsg("unsupported Unicode escape sequence"),
               errdetail("\\u0000 cannot be converted to text."),
                 report_json_context(lex)));
          }
          else if (GetDatabaseEncoding() == PG_UTF8)
          {
            unicode_to_utf8(ch, (unsigned char *) utf8str);
            utf8len = pg_utf_mblen((unsigned char *) utf8str);
            appendBinaryStringInfo(lex->strval, utf8str, utf8len);
          }
          else if (ch <= 0x007f)
          {
            /*
             * This is the only way to designate things like a
             * form feed character in JSON, so it's useful in all
             * encodings.
             */
            appendStringInfoChar(lex->strval, (char) ch);
          }
          else
          {
            ereport(ERROR,
                (errcode(ERRCODE_UNTRANSLATABLE_CHARACTER),
                 errmsg("unsupported Unicode escape sequence"),
                 errdetail("Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8."),
                 report_json_context(lex)));
          }

        }
      }
      else if (lex->strval != NULL)
      {
        if (hi_surrogate != -1)
          ereport(ERROR,
              (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
               errmsg("invalid input syntax for type json"),
               errdetail("Unicode low surrogate must follow a high surrogate."),
               report_json_context(lex)));

        switch (*s)
        {
          case '"':
          case '\\':
          case '/':
            appendStringInfoChar(lex->strval, *s);
            break;
          case 'b':
            appendStringInfoChar(lex->strval, '\b');
            break;
          case 'f':
            appendStringInfoChar(lex->strval, '\f');
            break;
          case 'n':
            appendStringInfoChar(lex->strval, '\n');
            break;
          case 'r':
            appendStringInfoChar(lex->strval, '\r');
            break;
          case 't':
            appendStringInfoChar(lex->strval, '\t');
            break;
          default:
            /* Not a valid string escape, so error out. */
            lex->token_terminator = s + pg_mblen(s);
            ereport(ERROR,
                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                 errmsg("invalid input syntax for type json"),
              errdetail("Escape sequence \"\\%s\" is invalid.",
                    extract_mb_char(s)),
                 report_json_context(lex)));
        }
      }
      else if (strchr("\"\\/bfnrt", *s) == NULL)
      {
        /*
         * Simpler processing if we're not bothered about de-escaping
         *
         * It's very tempting to remove the strchr() call here and
         * replace it with a switch statement, but testing so far has
         * shown it's not a performance win.
         */
        lex->token_terminator = s + pg_mblen(s);
        ereport(ERROR,
            (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
             errmsg("invalid input syntax for type json"),
             errdetail("Escape sequence \"\\%s\" is invalid.",
                   extract_mb_char(s)),
             report_json_context(lex)));
      }

    }
    else if (lex->strval != NULL)
    {
      if (hi_surrogate != -1)
        ereport(ERROR,
            (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
             errmsg("invalid input syntax for type json"),
             errdetail("Unicode low surrogate must follow a high surrogate."),
             report_json_context(lex)));

      appendStringInfoChar(lex->strval, *s);
    }

  }

  if (hi_surrogate != -1)
    ereport(ERROR,
        (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
         errmsg("invalid input syntax for type json"),
      errdetail("Unicode low surrogate must follow a high surrogate."),
         report_json_context(lex)));

  /* Hooray, we found the end of the string! */
  lex->prev_token_terminator = lex->token_terminator;
  lex->token_terminator = s + 1;
}

/*-------------------------------------------------------------------------
 * The next token in the input stream is known to be a number; lex it.
 *
 * In JSON, a number consists of four parts:
 *
 * (1) An optional minus sign ('-').
 *
 * (2) Either a single '0', or a string of one or more digits that does not
 *     begin with a '0'.
 *
 * (3) An optional decimal part, consisting of a period ('.') followed by
 *     one or more digits.  (Note: While this part can be omitted
 *     completely, it's not OK to have only the decimal point without
 *     any digits afterwards.)
 *
 * (4) An optional exponent part, consisting of 'e' or 'E', optionally
 *     followed by '+' or '-', followed by one or more digits.  (Note:
 *     As with the decimal part, if 'e' or 'E' is present, it must be
 *     followed by at least one digit.)
 *
 * The 's' argument to this function points to the ostensible beginning
 * of part 2 - i.e. the character after any optional minus sign, and the
 * first character of the string if there is none.
 *
 *-------------------------------------------------------------------------
 */
static inline void
json_lex_number(JsonLexContext *lex, char *s, bool *num_err)
{
  bool    error = false;
  char     *p;
  int     len;

  len = s - lex->input;
  /* Part (1): leading sign indicator. */
  /* Caller already did this for us; so do nothing. */

  /* Part (2): parse main digit string. */
  if (*s == '0')
  {
    s++;
    len++;
  }
  else if (*s >= '1' && *s <= '9')
  {
    do
    {
      s++;
      len++;
    } while (len < lex->input_length && *s >= '0' && *s <= '9');
  }
  else
    error = true;

  /* Part (3): parse optional decimal portion. */
  if (len < lex->input_length && *s == '.')
  {
    s++;
    len++;
    if (len == lex->input_length || *s < '0' || *s > '9')
      error = true;
    else
    {
      do
      {
        s++;
        len++;
      } while (len < lex->input_length && *s >= '0' && *s <= '9');
    }
  }

  /* Part (4): parse optional exponent. */
  if (len < lex->input_length && (*s == 'e' || *s == 'E'))
  {
    s++;
    len++;
    if (len < lex->input_length && (*s == '+' || *s == '-'))
    {
      s++;
      len++;
    }
    if (len == lex->input_length || *s < '0' || *s > '9')
      error = true;
    else
    {
      do
      {
        s++;
        len++;
      } while (len < lex->input_length && *s >= '0' && *s <= '9');
    }
  }

  /*
   * Check for trailing garbage.  As in json_lex(), any alphanumeric stuff
   * here should be considered part of the token for error-reporting
   * purposes.
   */
  for (p = s; len < lex->input_length && JSON_ALPHANUMERIC_CHAR(*p); p++, len++)
    error = true;

  if (num_err != NULL)
  {
    /* let the caller handle the error */
    *num_err = error;
  }
  else
  {
    lex->prev_token_terminator = lex->token_terminator;
    lex->token_terminator = p;
    if (error)
      report_invalid_token(lex);
  }
}

/*
 * Report a parse error.
 *
 * lex->token_start and lex->token_terminator must identify the current token.
 */
static void
report_parse_error(JsonParseContext ctx, JsonLexContext *lex)
{
  char     *token;
  int     toklen;

  /* Handle case where the input ended prematurely. */
  if (lex->token_start == NULL || lex->token_type == JSON_TOKEN_END)
    ereport(ERROR,
        (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
         errmsg("invalid input syntax for type json"),
         errdetail("The input string ended unexpectedly."),
         report_json_context(lex)));

  /* Separate out the current token. */
  toklen = lex->token_terminator - lex->token_start;
  token = palloc(toklen + 1);
  memcpy(token, lex->token_start, toklen);
  token[toklen] = '\0';

  /* Complain, with the appropriate detail message. */
  if (ctx == JSON_PARSE_END)
    ereport(ERROR,
        (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
         errmsg("invalid input syntax for type json"),
         errdetail("Expected end of input, but found \"%s\".",
               token),
         report_json_context(lex)));
  else
  {
    switch (ctx)
    {
      case JSON_PARSE_VALUE:
        ereport(ERROR,
            (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
             errmsg("invalid input syntax for type json"),
             errdetail("Expected JSON value, but found \"%s\".",
                   token),
             report_json_context(lex)));
        break;
      case JSON_PARSE_STRING:
        ereport(ERROR,
            (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
             errmsg("invalid input syntax for type json"),
             errdetail("Expected string, but found \"%s\".",
                   token),
             report_json_context(lex)));
        break;
      case JSON_PARSE_ARRAY_START:
        ereport(ERROR,
            (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
             errmsg("invalid input syntax for type json"),
             errdetail("Expected array element or \"]\", but found \"%s\".",
                   token),
             report_json_context(lex)));
        break;
      case JSON_PARSE_ARRAY_NEXT:
        ereport(ERROR,
            (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
             errmsg("invalid input syntax for type json"),
            errdetail("Expected \",\" or \"]\", but found \"%s\".",
                token),
             report_json_context(lex)));
        break;
      case JSON_PARSE_OBJECT_START:
        ereport(ERROR,
            (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
             errmsg("invalid input syntax for type json"),
           errdetail("Expected string or \"}\", but found \"%s\".",
                 token),
             report_json_context(lex)));
        break;
      case JSON_PARSE_OBJECT_LABEL:
        ereport(ERROR,
            (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
             errmsg("invalid input syntax for type json"),
             errdetail("Expected \":\", but found \"%s\".",
                   token),
             report_json_context(lex)));
        break;
      case JSON_PARSE_OBJECT_NEXT:
        ereport(ERROR,
            (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
             errmsg("invalid input syntax for type json"),
            errdetail("Expected \",\" or \"}\", but found \"%s\".",
                token),
             report_json_context(lex)));
        break;
      case JSON_PARSE_OBJECT_COMMA:
        ereport(ERROR,
            (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
             errmsg("invalid input syntax for type json"),
             errdetail("Expected string, but found \"%s\".",
                   token),
             report_json_context(lex)));
        break;
      default:
        elog(ERROR, "unexpected json parse state: %d", ctx);
    }
  }
}

/*
 * Report an invalid input token.
 *
 * lex->token_start and lex->token_terminator must identify the token.
 */
static void
report_invalid_token(JsonLexContext *lex)
{
  char     *token;
  int     toklen;

  /* Separate out the offending token. */
  toklen = lex->token_terminator - lex->token_start;
  token = palloc(toklen + 1);
  memcpy(token, lex->token_start, toklen);
  token[toklen] = '\0';

  ereport(ERROR,
      (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
       errmsg("invalid input syntax for type json"),
       errdetail("Token \"%s\" is invalid.", token),
       report_json_context(lex)));
}

/*
 * Report a CONTEXT line for bogus JSON input.
 *
 * lex->token_terminator must be set to identify the spot where we detected
 * the error.  Note that lex->token_start might be NULL, in case we recognized
 * error at EOF.
 *
 * The return value isn't meaningful, but we make it non-void so that this
 * can be invoked inside ereport().
 */
static int
report_json_context(JsonLexContext *lex)
{
  const char *context_start;
  const char *context_end;
  const char *line_start;
  int     line_number;
  char     *ctxt;
  int     ctxtlen;
  const char *prefix;
  const char *suffix;

  /* Choose boundaries for the part of the input we will display */
  context_start = lex->input;
  context_end = lex->token_terminator;
  line_start = context_start;
  line_number = 1;
  for (;;)
  {
    /* Always advance over newlines */
    if (context_start < context_end && *context_start == '\n')
    {
      context_start++;
      line_start = context_start;
      line_number++;
      continue;
    }
    /* Otherwise, done as soon as we are close enough to context_end */
    if (context_end - context_start < 50)
      break;
    /* Advance to next multibyte character */
    if (IS_HIGHBIT_SET(*context_start))
      context_start += pg_mblen(context_start);
    else
      context_start++;
  }

  /*
   * We add "..." to indicate that the excerpt doesn't start at the
   * beginning of the line ... but if we're within 3 characters of the
   * beginning of the line, we might as well just show the whole line.
   */
  if (context_start - line_start <= 3)
    context_start = line_start;

  /* Get a null-terminated copy of the data to present */
  ctxtlen = context_end - context_start;
  ctxt = palloc(ctxtlen + 1);
  memcpy(ctxt, context_start, ctxtlen);
  ctxt[ctxtlen] = '\0';

  /*
   * Show the context, prefixing "..." if not starting at start of line, and
   * suffixing "..." if not ending at end of line.
   */
  prefix = (context_start > line_start) ? "..." : "";
  suffix = (lex->token_type != JSON_TOKEN_END && context_end - lex->input < lex->input_length && *context_end != '\n' && *context_end != '\r') ? "..." : "";

  return errcontext("JSON data, line %d: %s%s%s",
            line_number, prefix, ctxt, suffix);
}

/*
 * Extract a single, possibly multi-byte char from the input string.
 */
static char *
extract_mb_char(char *s)
{
  char     *res;
  int     len;

  len = pg_mblen(s);
  res = palloc(len + 1);
  memcpy(res, s, len);
  res[len] = '\0';

  return res;
}

/*
 * Determine how we want to print values of a given type in datum_to_json.
 *
 * Given the datatype OID, return its JsonTypeCategory, as well as the type's
 * output function OID.  If the returned category is JSONTYPE_CAST, we
 * return the OID of the type->JSON cast function instead.
 */
static void
json_categorize_type(Oid typoid,
           JsonTypeCategory *tcategory,
           Oid *outfuncoid)
{
  bool    typisvarlena;

  /* Look through any domain */
  typoid = getBaseType(typoid);

  *outfuncoid = InvalidOid;

  /*
   * We need to get the output function for everything except date and
   * timestamp types, array and composite types, booleans, and non-builtin
   * types where there's a cast to json.
   */

  switch (typoid)
  {
    case BOOLOID:
      *tcategory = JSONTYPE_BOOL;
      break;

    case INT2OID:
    case INT4OID:
    case INT8OID:
    case FLOAT4OID:
    case FLOAT8OID:
    case NUMERICOID:
      getTypeOutputInfo(typoid, outfuncoid, &typisvarlena);
      *tcategory = JSONTYPE_NUMERIC;
      break;

    case DATEOID:
      *tcategory = JSONTYPE_DATE;
      break;

    case TIMESTAMPOID:
      *tcategory = JSONTYPE_TIMESTAMP;
      break;

    case TIMESTAMPTZOID:
      *tcategory = JSONTYPE_TIMESTAMPTZ;
      break;

    case JSONOID:
    case JSONBOID:
      getTypeOutputInfo(typoid, outfuncoid, &typisvarlena);
      *tcategory = JSONTYPE_JSON;
      break;

    default:
      /* Check for arrays and composites */
      if (OidIsValid(get_element_type(typoid)))
        *tcategory = JSONTYPE_ARRAY;
      else if (type_is_rowtype(typoid))
        *tcategory = JSONTYPE_COMPOSITE;
      else
      {
        /* It's probably the general case ... */
        *tcategory = JSONTYPE_OTHER;
        /* but let's look for a cast to json, if it's not built-in */
        if (typoid >= FirstNormalObjectId)
        {
          Oid     castfunc;
          bool ctype;

          ctype = find_coercion_pathway(JSONOID, typoid,
                          COERCION_EXPLICIT,
                          &castfunc);
          if (ctype && OidIsValid(castfunc))
          {
            *tcategory = JSONTYPE_CAST;
            *outfuncoid = castfunc;
          }
          else
          {
            /* non builtin type with no cast */
            getTypeOutputInfo(typoid, outfuncoid, &typisvarlena);
          }
        }
        else
        {
          /* any other builtin type */
          getTypeOutputInfo(typoid, outfuncoid, &typisvarlena);
        }
      }
      break;
  }
}

/*
 * Turn a Datum into JSON text, appending the string to "result".
 *
 * tcategory and outfuncoid are from a previous call to json_categorize_type,
 * except that if is_null is true then they can be invalid.
 *
 * If key_scalar is true, the value is being printed as a key, so insist
 * it's of an acceptable type, and force it to be quoted.
 */
static void
datum_to_json(Datum val, bool is_null, StringInfo result,
        JsonTypeCategory tcategory, Oid outfuncoid,
        bool key_scalar)
{
  char     *outputstr;
  text     *jsontext;

  check_stack_depth();

  /* callers are expected to ensure that null keys are not passed in */
  Assert(!(key_scalar && is_null));

  if (is_null)
  {
    appendStringInfoString(result, "null");
    return;
  }

  if (key_scalar &&
    (tcategory == JSONTYPE_ARRAY ||
     tcategory == JSONTYPE_COMPOSITE ||
     tcategory == JSONTYPE_JSON ||
     tcategory == JSONTYPE_CAST))
    ereport(ERROR,
        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
     errmsg("key value must be scalar, not array, composite, or json")));

  switch (tcategory)
  {
    case JSONTYPE_ARRAY:
      array_to_json_internal(val, result, false);
      break;
    case JSONTYPE_COMPOSITE:
      composite_to_json(val, result, false);
      break;
    case JSONTYPE_BOOL:
      outputstr = DatumGetBool(val) ? "true" : "false";
      if (key_scalar)
        escape_json(result, outputstr);
      else
        appendStringInfoString(result, outputstr);
      break;
    case JSONTYPE_NUMERIC:
      outputstr = OidOutputFunctionCall(outfuncoid, val);

      /*
       * Don't call escape_json for a non-key if it's a valid JSON
       * number.
       */
      if (!key_scalar && IsValidJsonNumber(outputstr, strlen(outputstr)))
        appendStringInfoString(result, outputstr);
      else
        escape_json(result, outputstr);
      pfree(outputstr);
      break;
    case JSONTYPE_DATE:
      {
        DateADT   date;
        struct pg_tm tm;
        char    buf[MAXDATELEN + 1];

        date = DatumGetDateADT(val);

        if (DATE_NOT_FINITE(date))
        {
          /* we have to format infinity ourselves */
          appendStringInfoString(result, DT_INFINITY);
        }
        else
        {
          j2date(date + POSTGRES_EPOCH_JDATE,
               &(tm.tm_year), &(tm.tm_mon), &(tm.tm_mday));
          EncodeDateOnly(&tm, USE_XSD_DATES, buf);
          appendStringInfo(result, "\"%s\"", buf);
        }
      }
      break;
    case JSONTYPE_TIMESTAMP:
      {
        Timestamp timestamp;
        struct pg_tm tm;
        fsec_t    fsec;
        char    buf[MAXDATELEN + 1];

        timestamp = DatumGetTimestamp(val);

        if (TIMESTAMP_NOT_FINITE(timestamp))
        {
          /* we have to format infinity ourselves */
          appendStringInfoString(result, DT_INFINITY);
        }
        else if (timestamp2tm(timestamp, NULL, &tm, &fsec, NULL, NULL) == 0)
        {
          int tzp = 0;
          const char *tzn = NULL;
          EncodeDateTime(&tm, fsec, &tzp, &tzn, USE_XSD_DATES, buf);
          appendStringInfo(result, "\"%s\"", buf);
        }
        else
          ereport(ERROR,
              (errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
               errmsg("timestamp out of range")));
      }
      break;
    case JSONTYPE_TIMESTAMPTZ:
      {
        TimestampTz timestamp;
        struct pg_tm tm;
        int     tz;
        fsec_t    fsec;
        const char *tzn = NULL;
        char    buf[MAXDATELEN + 1];

        timestamp = DatumGetTimestamp(val);

        if (TIMESTAMP_NOT_FINITE(timestamp))
        {
          /* we have to format infinity ourselves */
          appendStringInfoString(result, DT_INFINITY);
        }
        else if (timestamp2tm(timestamp, &tz, &tm, &fsec, &tzn, NULL) == 0)
        {
          EncodeDateTime(&tm, fsec, &tz, &tzn, USE_XSD_DATES, buf);
          appendStringInfo(result, "\"%s\"", buf);
        }
        else
          ereport(ERROR,
              (errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
               errmsg("timestamp out of range")));
      }
      break;
    case JSONTYPE_JSON:
      /* JSON and JSONB output will already be escaped */
      outputstr = OidOutputFunctionCall(outfuncoid, val);
      appendStringInfoString(result, outputstr);
      pfree(outputstr);
      break;
    case JSONTYPE_CAST:
      /* outfuncoid refers to a cast function, not an output function */
      jsontext = DatumGetTextP(OidFunctionCall1(outfuncoid, val));
      outputstr = text_to_cstring(jsontext);
      appendStringInfoString(result, outputstr);
      pfree(outputstr);
      pfree(jsontext);
      break;
    default:
      outputstr = OidOutputFunctionCall(outfuncoid, val);
      escape_json(result, outputstr);
      pfree(outputstr);
      break;
  }
}

/*
 * Process a single dimension of an array.
 * If it's the innermost dimension, output the values, otherwise call
 * ourselves recursively to process the next dimension.
 */
static void
array_dim_to_json(StringInfo result, int dim, int ndims, int *dims, Datum *vals,
          bool *nulls, int *valcount, JsonTypeCategory tcategory,
          Oid outfuncoid, bool use_line_feeds)
{
  int     i;
  const char *sep;

  Assert(dim < ndims);

  sep = use_line_feeds ? ",\n " : ",";

  appendStringInfoChar(result, '[');

  for (i = 1; i <= dims[dim]; i++)
  {
    if (i > 1)
      appendStringInfoString(result, sep);

    if (dim + 1 == ndims)
    {
      datum_to_json(vals[*valcount], nulls[*valcount], result, tcategory,
              outfuncoid, false);
      (*valcount)++;
    }
    else
    {
      /*
       * Do we want line feeds on inner dimensions of arrays? For now
       * we'll say no.
       */
      array_dim_to_json(result, dim + 1, ndims, dims, vals, nulls,
                valcount, tcategory, outfuncoid, false);
    }
  }

  appendStringInfoChar(result, ']');
}

/*
 * Turn an array into JSON.
 */
static void
array_to_json_internal(Datum array, StringInfo result, bool use_line_feeds)
{
  ArrayType  *v = DatumGetArrayTypeP(array);
  Oid     element_type = ARR_ELEMTYPE(v);
  int      *dim;
  int     ndim;
  int     nitems;
  int     count = 0;
  Datum    *elements;
  bool     *nulls;
  int16   typlen;
  bool    typbyval;
  char    typalign;
  JsonTypeCategory tcategory;
  Oid     outfuncoid;

  ndim = ARR_NDIM(v);
  dim = ARR_DIMS(v);
  nitems = ArrayGetNItems(ndim, dim);

  if (nitems <= 0)
  {
    appendStringInfoString(result, "[]");
    return;
  }

  get_typlenbyvalalign(element_type,
             &typlen, &typbyval, &typalign);

  json_categorize_type(element_type,
             &tcategory, &outfuncoid);

  deconstruct_array(v, element_type, typlen, typbyval,
            typalign, &elements, &nulls,
            &nitems);

  array_dim_to_json(result, 0, ndim, dim, elements, nulls, &count, tcategory,
            outfuncoid, use_line_feeds);

  pfree(elements);
  pfree(nulls);
}

/*
 * Turn a composite / record into JSON.
 */
static void
composite_to_json(Datum composite, StringInfo result, bool use_line_feeds)
{
  HeapTupleHeader td;
  Oid     tupType;
  int32   tupTypmod;
  TupleDesc tupdesc;
  HeapTupleData tmptup,
         *tuple;
  int     i;
  bool    needsep = false;
  const char *sep;

  sep = use_line_feeds ? ",\n " : ",";

  td = DatumGetHeapTupleHeader(composite);

  /* Extract rowtype info and find a tupdesc */
  tupType = HeapTupleHeaderGetTypeId(td);
  tupTypmod = HeapTupleHeaderGetTypMod(td);
  tupdesc = lookup_rowtype_tupdesc(tupType, tupTypmod);

  /* Build a temporary HeapTuple control structure */
  tmptup.t_len = HeapTupleHeaderGetDatumLength(td);
  tmptup.t_data = td;
  tuple = &tmptup;

  appendStringInfoChar(result, '{');

  for (i = 0; i < tupdesc->natts; i++)
  {
    Datum   val;
    bool    isnull;
    char     *attname;
    JsonTypeCategory tcategory;
    Oid     outfuncoid;

    if (tupdesc->attrs[i]->attisdropped)
      continue;

    if (needsep)
      appendStringInfoString(result, sep);
    needsep = true;

    attname = NameStr(tupdesc->attrs[i]->attname);
    escape_json(result, attname);
    appendStringInfoChar(result, ':');

    val = heap_getattr(tuple, i + 1, tupdesc, &isnull);

    if (isnull)
    {
      tcategory = JSONTYPE_NULL;
      outfuncoid = InvalidOid;
    }
    else
      json_categorize_type(tupdesc->attrs[i]->atttypid,
                 &tcategory, &outfuncoid);

    datum_to_json(val, isnull, result, tcategory, outfuncoid, false);
  }

  appendStringInfoChar(result, '}');
  ReleaseTupleDesc(tupdesc);
}

/*
 * Append JSON text for "val" to "result".
 *
 * This is just a thin wrapper around datum_to_json.  If the same type will be
 * printed many times, avoid using this; better to do the json_categorize_type
 * lookups only once.
 */
static void
add_json(Datum val, bool is_null, StringInfo result,
     Oid val_type, bool key_scalar)
{
  JsonTypeCategory tcategory;
  Oid     outfuncoid;

  if (val_type == InvalidOid)
    ereport(ERROR,
        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
         errmsg("could not determine input data type")));

  if (is_null)
  {
    tcategory = JSONTYPE_NULL;
    outfuncoid = InvalidOid;
  }
  else
    json_categorize_type(val_type,
               &tcategory, &outfuncoid);

  datum_to_json(val, is_null, result, tcategory, outfuncoid, key_scalar);
}

/*
 * SQL function array_to_json(row)
 */
extern Datum
array_to_json(PG_FUNCTION_ARGS)
{
  Datum   array = PG_GETARG_DATUM(0);
  StringInfo  result;

  result = makeStringInfo();

  array_to_json_internal(array, result, false);

  PG_RETURN_TEXT_P(cstring_to_text_with_len(result->data, result->len));
}

/*
 * SQL function array_to_json(row, prettybool)
 */
extern Datum
array_to_json_pretty(PG_FUNCTION_ARGS)
{
  Datum   array = PG_GETARG_DATUM(0);
  bool    use_line_feeds = PG_GETARG_BOOL(1);
  StringInfo  result;

  result = makeStringInfo();

  array_to_json_internal(array, result, use_line_feeds);

  PG_RETURN_TEXT_P(cstring_to_text_with_len(result->data, result->len));
}

/*
 * SQL function row_to_json(row)
 */
extern Datum
row_to_json(PG_FUNCTION_ARGS)
{
  Datum   array = PG_GETARG_DATUM(0);
  StringInfo  result;

  result = makeStringInfo();

  composite_to_json(array, result, false);

  PG_RETURN_TEXT_P(cstring_to_text_with_len(result->data, result->len));
}

/*
 * SQL function row_to_json(row, prettybool)
 */
extern Datum
row_to_json_pretty(PG_FUNCTION_ARGS)
{
  Datum   array = PG_GETARG_DATUM(0);
  bool    use_line_feeds = PG_GETARG_BOOL(1);
  StringInfo  result;

  result = makeStringInfo();

  composite_to_json(array, result, use_line_feeds);

  PG_RETURN_TEXT_P(cstring_to_text_with_len(result->data, result->len));
}

/*
 * SQL function to_json(anyvalue)
 */
Datum
to_json(PG_FUNCTION_ARGS)
{
  Datum   val = PG_GETARG_DATUM(0);
  Oid     val_type = get_fn_expr_argtype(fcinfo->flinfo, 0);
  StringInfo  result;
  JsonTypeCategory tcategory;
  Oid     outfuncoid;

  if (val_type == InvalidOid)
    ereport(ERROR,
        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
         errmsg("could not determine input data type")));

  json_categorize_type(val_type,
             &tcategory, &outfuncoid);

  result = makeStringInfo();

  datum_to_json(val, false, result, tcategory, outfuncoid, false);

  PG_RETURN_TEXT_P(cstring_to_text_with_len(result->data, result->len));
}

/*
 * json_agg transition function
 *
 * aggregate input column as a json array value.
 */
Datum
json_agg_transfn(PG_FUNCTION_ARGS)
{
  MemoryContext aggcontext,
        oldcontext;
  JsonAggState  *state;
  Datum   val;

  if (!AggCheckCallContext(fcinfo, &aggcontext))
  {
    /* cannot be called directly because of internal-type argument */
    elog(ERROR, "json_agg_transfn called in non-aggregate context");
  }

  if (PG_ARGISNULL(0))
  {
    Oid         arg_type = get_fn_expr_argtype(fcinfo->flinfo, 1);

    if (arg_type == InvalidOid)
      ereport(ERROR,
          (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
           errmsg("could not determine input data type")));

    /*
     * Make this state object in a context where it will persist for the
     * duration of the aggregate call.  MemoryContextSwitchTo is only
     * needed the first time, as the StringInfo routines make sure they
     * use the right context to enlarge the object if necessary.
     */
    oldcontext = MemoryContextSwitchTo(aggcontext);
    state = (JsonAggState *) palloc(sizeof(JsonAggState));
    state->str = makeStringInfo();
    MemoryContextSwitchTo(oldcontext);

    appendStringInfoChar(state->str, '[');
    json_categorize_type(arg_type,&state->val_category,
               &state->val_output_func);
  }
  else
  {
    state = (JsonAggState *) PG_GETARG_POINTER(0);
    appendStringInfoString(state->str, ", ");
  }

  /* fast path for NULLs */
  if (PG_ARGISNULL(1))
  {
    datum_to_json((Datum) 0, true, state->str, JSONTYPE_NULL,
            InvalidOid, false);
    PG_RETURN_POINTER(state);
  }

  val = PG_GETARG_DATUM(1);

  /* add some whitespace if structured type and not first item */
  if (!PG_ARGISNULL(0) &&
    (state->val_category == JSONTYPE_ARRAY ||
     state->val_category == JSONTYPE_COMPOSITE))
  {
    appendStringInfoString(state->str, "\n ");
  }

  datum_to_json(val, false, state->str, state->val_category,
          state->val_output_func, false);

  /*
   * The transition type for array_agg() is declared to be "internal", which
   * is a pass-by-value type the same size as a pointer.  So we can safely
   * pass the JsonAggState pointer through nodeAgg.c's machinations.
   */
  PG_RETURN_POINTER(state);
}

/*
 * json_agg final function
 */
Datum
json_agg_finalfn(PG_FUNCTION_ARGS)
{
  JsonAggState  *state;

  /* cannot be called directly because of internal-type argument */
  Assert(AggCheckCallContext(fcinfo, NULL));

  state = PG_ARGISNULL(0) ?
    NULL :
    (JsonAggState *) PG_GETARG_POINTER(0);

  /* NULL result for no rows in, as is standard with aggregates */
  if (state == NULL)
    PG_RETURN_NULL();

  /* Else return state with appropriate array terminator added */
  PG_RETURN_TEXT_P(catenate_stringinfo_string(state->str, "]"));
}

/*
 * json_object_agg transition function.
 *
 * aggregate two input columns as a single json object value.
 */
Datum
json_object_agg_transfn(PG_FUNCTION_ARGS)
{
  MemoryContext aggcontext,
        oldcontext;
  JsonAggState  *state;
  Datum   arg;

  if (!AggCheckCallContext(fcinfo, &aggcontext))
  {
    /* cannot be called directly because of internal-type argument */
    elog(ERROR, "json_object_agg_transfn called in non-aggregate context");
  }

  if (PG_ARGISNULL(0))
  {
    Oid     arg_type;

    /*
     * Make the StringInfo in a context where it will persist for the
     * duration of the aggregate call. Switching context is only needed
     * for this initial step, as the StringInfo routines make sure they
     * use the right context to enlarge the object if necessary.
     */
    oldcontext = MemoryContextSwitchTo(aggcontext);
    state = (JsonAggState *) palloc(sizeof(JsonAggState));
    state->str = makeStringInfo();
    MemoryContextSwitchTo(oldcontext);

    arg_type = get_fn_expr_argtype(fcinfo->flinfo, 1);

    if (arg_type == InvalidOid)
      ereport(ERROR,
          (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
           errmsg("could not determine data type for argument 1")));

    json_categorize_type(arg_type,&state->key_category,
               &state->key_output_func);

    arg_type = get_fn_expr_argtype(fcinfo->flinfo, 2);

    if (arg_type == InvalidOid)
      ereport(ERROR,
          (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
           errmsg("could not determine data type for argument 2")));

    json_categorize_type(arg_type,&state->val_category,
               &state->val_output_func);

    appendStringInfoString(state->str, "{ ");
  }
  else
  {
    state = (JsonAggState *) PG_GETARG_POINTER(0);
    appendStringInfoString(state->str, ", ");
  }

  /*
   * Note: since json_object_agg() is declared as taking type "any", the
   * parser will not do any type conversion on unknown-type literals (that
   * is, undecorated strings or NULLs).  Such values will arrive here as
   * type UNKNOWN, which fortunately does not matter to us, since
   * unknownout() works fine.
   */

  if (PG_ARGISNULL(1))
    ereport(ERROR,
        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
         errmsg("field name must not be null")));

  arg = PG_GETARG_DATUM(1);

  datum_to_json(arg, false, state->str, state->key_category,
          state->key_output_func, true);

  appendStringInfoString(state->str, " : ");

  if (PG_ARGISNULL(2))
    arg = (Datum) 0;
  else
    arg = PG_GETARG_DATUM(2);

  datum_to_json(arg, PG_ARGISNULL(2), state->str, state->val_category,
          state->val_output_func, false);

  PG_RETURN_POINTER(state);
}

/*
 * json_object_agg final function.
 */
Datum
json_object_agg_finalfn(PG_FUNCTION_ARGS)
{
  JsonAggState  *state;

  /* cannot be called directly because of internal-type argument */
  Assert(AggCheckCallContext(fcinfo, NULL));

  state = PG_ARGISNULL(0) ? NULL : (JsonAggState *) PG_GETARG_POINTER(0);

  /* NULL result for no rows in, as is standard with aggregates */
  if (state == NULL)
    PG_RETURN_NULL();

  /* Else return state with appropriate object terminator added */
  PG_RETURN_TEXT_P(catenate_stringinfo_string(state->str, " }"));
}

/*
 * Helper function for aggregates: return given StringInfo's contents plus
 * specified trailing string, as a text datum.  We need this because aggregate
 * final functions are not allowed to modify the aggregate state.
 */
static text *
catenate_stringinfo_string(StringInfo buffer, const char *addon)
{
  /* custom version of cstring_to_text_with_len */
  int     buflen = buffer->len;
  int     addlen = strlen(addon);
  text     *result = (text *) palloc(buflen + addlen + VARHDRSZ);

  SET_VARSIZE(result, buflen + addlen + VARHDRSZ);
  memcpy(VARDATA(result), buffer->data, buflen);
  memcpy(VARDATA(result) + buflen, addon, addlen);

  return result;
}

/*
 * SQL function json_build_object(variadic "any")
 */
Datum
json_build_object(PG_FUNCTION_ARGS)
{
  int     nargs = PG_NARGS();
  int     i;
  Datum   arg;
  const char *sep = "";
  StringInfo  result;
  Oid     val_type;

  if (nargs % 2 != 0)
    ereport(ERROR,
        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
         errmsg("argument list must have even number of elements"),
         errhint("The arguments of json_build_object() must consist of alternating keys and values.")));

  result = makeStringInfo();

  appendStringInfoChar(result, '{');

  for (i = 0; i < nargs; i += 2)
  {
    /*
     * Note: since json_build_object() is declared as taking type "any",
     * the parser will not do any type conversion on unknown-type literals
     * (that is, undecorated strings or NULLs).  Such values will arrive
     * here as type UNKNOWN, which fortunately does not matter to us,
     * since unknownout() works fine.
     */
    appendStringInfoString(result, sep);
    sep = ", ";

    /* process key */
    val_type = get_fn_expr_argtype(fcinfo->flinfo, i);

    if (val_type == InvalidOid)
      ereport(ERROR,
          (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
           errmsg("could not determine data type for argument %d",
              i + 1)));

    if (PG_ARGISNULL(i))
      ereport(ERROR,
          (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
           errmsg("argument %d cannot be null", i + 1),
           errhint("Object keys should be text.")));

    arg = PG_GETARG_DATUM(i);

    add_json(arg, false, result, val_type, true);

    appendStringInfoString(result, " : ");

    /* process value */
    val_type = get_fn_expr_argtype(fcinfo->flinfo, i + 1);

    if (val_type == InvalidOid)
      ereport(ERROR,
          (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
           errmsg("could not determine data type for argument %d",
              i + 2)));

    if (PG_ARGISNULL(i + 1))
      arg = (Datum) 0;
    else
      arg = PG_GETARG_DATUM(i + 1);

    add_json(arg, PG_ARGISNULL(i + 1), result, val_type, false);
  }

  appendStringInfoChar(result, '}');

  PG_RETURN_TEXT_P(cstring_to_text_with_len(result->data, result->len));
}

/*
 * degenerate case of json_build_object where it gets 0 arguments.
 */
Datum
json_build_object_noargs(PG_FUNCTION_ARGS)
{
  PG_RETURN_TEXT_P(cstring_to_text_with_len("{}", 2));
}

/*
 * SQL function json_build_array(variadic "any")
 */
Datum
json_build_array(PG_FUNCTION_ARGS)
{
  int     nargs = PG_NARGS();
  int     i;
  Datum   arg;
  const char *sep = "";
  StringInfo  result;
  Oid     val_type;

  result = makeStringInfo();

  appendStringInfoChar(result, '[');

  for (i = 0; i < nargs; i++)
  {
    /*
     * Note: since json_build_array() is declared as taking type "any",
     * the parser will not do any type conversion on unknown-type literals
     * (that is, undecorated strings or NULLs).  Such values will arrive
     * here as type UNKNOWN, which fortunately does not matter to us,
     * since unknownout() works fine.
     */
    appendStringInfoString(result, sep);
    sep = ", ";

    val_type = get_fn_expr_argtype(fcinfo->flinfo, i);

    if (val_type == InvalidOid)
      ereport(ERROR,
          (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
           errmsg("could not determine data type for argument %d",
              i + 1)));

    if (PG_ARGISNULL(i))
      arg = (Datum) 0;
    else
      arg = PG_GETARG_DATUM(i);

    add_json(arg, PG_ARGISNULL(i), result, val_type, false);
  }

  appendStringInfoChar(result, ']');

  PG_RETURN_TEXT_P(cstring_to_text_with_len(result->data, result->len));
}

/*
 * degenerate case of json_build_array where it gets 0 arguments.
 */
Datum
json_build_array_noargs(PG_FUNCTION_ARGS)
{
  PG_RETURN_TEXT_P(cstring_to_text_with_len("[]", 2));
}

/*
 * SQL function json_object(text[])
 *
 * take a one or two dimensional array of text as key/value pairs
 * for a json object.
 */
Datum
json_object(PG_FUNCTION_ARGS)
{
  ArrayType  *in_array = PG_GETARG_ARRAYTYPE_P(0);
  int     ndims = ARR_NDIM(in_array);
  StringInfoData result;
  Datum    *in_datums;
  bool     *in_nulls;
  int     in_count,
        count,
        i;
  text     *rval;
  char     *v;

  switch (ndims)
  {
    case 0:
      PG_RETURN_DATUM(CStringGetTextDatum("{}"));
      break;

    case 1:
      if ((ARR_DIMS(in_array)[0]) % 2)
        ereport(ERROR,
            (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
             errmsg("array must have even number of elements")));
      break;

    case 2:
      if ((ARR_DIMS(in_array)[1]) != 2)
        ereport(ERROR,
            (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
             errmsg("array must have two columns")));
      break;

    default:
      ereport(ERROR,
          (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
           errmsg("wrong number of array subscripts")));
  }

  deconstruct_array(in_array,
            TEXTOID, -1, false, 'i',
            &in_datums, &in_nulls, &in_count);

  count = in_count / 2;

  initStringInfo(&result);

  appendStringInfoChar(&result, '{');

  for (i = 0; i < count; ++i)
  {
    if (in_nulls[i * 2])
      ereport(ERROR,
          (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
           errmsg("null value not allowed for object key")));

    v = TextDatumGetCString(in_datums[i * 2]);
    if (i > 0)
      appendStringInfoString(&result, ", ");
    escape_json(&result, v);
    appendStringInfoString(&result, " : ");
    pfree(v);
    if (in_nulls[i * 2 + 1])
      appendStringInfoString(&result, "null");
    else
    {
      v = TextDatumGetCString(in_datums[i * 2 + 1]);
      escape_json(&result, v);
      pfree(v);
    }
  }

  appendStringInfoChar(&result, '}');

  pfree(in_datums);
  pfree(in_nulls);

  rval = cstring_to_text_with_len(result.data, result.len);
  pfree(result.data);

  PG_RETURN_TEXT_P(rval);

}

/*
 * SQL function json_object(text[], text[])
 *
 * take separate key and value arrays of text to construct a json object
 * pairwise.
 */
Datum
json_object_two_arg(PG_FUNCTION_ARGS)
{
  ArrayType  *key_array = PG_GETARG_ARRAYTYPE_P(0);
  ArrayType  *val_array = PG_GETARG_ARRAYTYPE_P(1);
  int     nkdims = ARR_NDIM(key_array);
  int     nvdims = ARR_NDIM(val_array);
  StringInfoData result;
  Datum    *key_datums,
         *val_datums;
  bool     *key_nulls,
         *val_nulls;
  int     key_count,
        val_count,
        i;
  text     *rval;
  char     *v;

  if (nkdims > 1 || nkdims != nvdims)
    ereport(ERROR,
        (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
         errmsg("wrong number of array subscripts")));

  if (nkdims == 0)
    PG_RETURN_DATUM(CStringGetTextDatum("{}"));

  deconstruct_array(key_array,
            TEXTOID, -1, false, 'i',
            &key_datums, &key_nulls, &key_count);

  deconstruct_array(val_array,
            TEXTOID, -1, false, 'i',
            &val_datums, &val_nulls, &val_count);

  if (key_count != val_count)
    ereport(ERROR,
        (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
         errmsg("mismatched array dimensions")));

  initStringInfo(&result);

  appendStringInfoChar(&result, '{');

  for (i = 0; i < key_count; ++i)
  {
    if (key_nulls[i])
      ereport(ERROR,
          (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
           errmsg("null value not allowed for object key")));

    v = TextDatumGetCString(key_datums[i]);
    if (i > 0)
      appendStringInfoString(&result, ", ");
    escape_json(&result, v);
    appendStringInfoString(&result, " : ");
    pfree(v);
    if (val_nulls[i])
      appendStringInfoString(&result, "null");
    else
    {
      v = TextDatumGetCString(val_datums[i]);
      escape_json(&result, v);
      pfree(v);
    }
  }

  appendStringInfoChar(&result, '}');

  pfree(key_datums);
  pfree(key_nulls);
  pfree(val_datums);
  pfree(val_nulls);

  rval = cstring_to_text_with_len(result.data, result.len);
  pfree(result.data);

  PG_RETURN_TEXT_P(rval);
}


/*
 * Produce a JSON string literal, properly escaping characters in the text.
 */
void
escape_json(StringInfo buf, const char *str)
{
  const char *p;

  appendStringInfoCharMacro(buf, '\"');
  for (p = str; *p; p++)
  {
    switch (*p)
    {
      case '\b':
        appendStringInfoString(buf, "\\b");
        break;
      case '\f':
        appendStringInfoString(buf, "\\f");
        break;
      case '\n':
        appendStringInfoString(buf, "\\n");
        break;
      case '\r':
        appendStringInfoString(buf, "\\r");
        break;
      case '\t':
        appendStringInfoString(buf, "\\t");
        break;
      case '"':
        appendStringInfoString(buf, "\\\"");
        break;
      case '\\':
        appendStringInfoString(buf, "\\\\");
        break;
      default:
        if ((unsigned char) *p < ' ')
          appendStringInfo(buf, "\\u%04x", (int) *p);
        else
          appendStringInfoCharMacro(buf, *p);
        break;
    }
  }
  appendStringInfoCharMacro(buf, '\"');
}

/*
 * SQL function json_typeof(json) -> text
 *
 * Returns the type of the outermost JSON value as TEXT.  Possible types are
 * "object", "array", "string", "number", "boolean", and "null".
 *
 * Performs a single call to json_lex() to get the first token of the supplied
 * value.  This initial token uniquely determines the value's type.  As our
 * input must already have been validated by json_in() or json_recv(), the
 * initial token should never be JSON_TOKEN_OBJECT_END, JSON_TOKEN_ARRAY_END,
 * JSON_TOKEN_COLON, JSON_TOKEN_COMMA, or JSON_TOKEN_END.
 */
Datum
json_typeof(PG_FUNCTION_ARGS)
{
  text     *json;

  JsonLexContext *lex;
  JsonTokenType tok;
  char     *type;

  json = PG_GETARG_TEXT_P(0);
  lex = makeJsonLexContext(json, false);

  /* Lex exactly one token from the input and check its type. */
  json_lex(lex);
  tok = lex_peek(lex);
  switch (tok)
  {
    case JSON_TOKEN_OBJECT_START:
      type = "object";
      break;
    case JSON_TOKEN_ARRAY_START:
      type = "array";
      break;
    case JSON_TOKEN_STRING:
      type = "string";
      break;
    case JSON_TOKEN_NUMBER:
      type = "number";
      break;
    case JSON_TOKEN_TRUE:
    case JSON_TOKEN_FALSE:
      type = "boolean";
      break;
    case JSON_TOKEN_NULL:
      type = "null";
      break;
    default:
      elog(ERROR, "unexpected json token: %d", tok);
  }

  PG_RETURN_TEXT_P(cstring_to_text(type));
}
